This invention relates to an endoscope in which a gas feed passage, and a liquid feed passage to carry gas and liquid, are formed in a main body.
In some endoscopes, a liquid feed passage is formed internally, a liquid inlet of the liquid feed passage is formed in a connector attached to a forward end of a universal cord, and a liquid outlet is formed in the distal end portion of the endoscope. Supplied through the liquid feed passage, a medical fluid may be sprayed in a body cavity, or water may be used to clean the outer surface of an objective lens. When using the endoscopes of this type for liquid feeding operation, the liquid would remain in the liquid feed passage after use if the use of the endoscope is suspended under a liquid feeding condition. In this case, if the liquid remaining in the liquid feed passage is left as it is, it could spoil or become contaminated by germs, etc. Thus, if the endoscope is used again with the liquid still remaining in the liquid feed passage, B-type hepatitis or hospital infection may be caused.
Accordingly, there has been proposed an improved endoscope as stated in Japanese Patent Disclosure No. 166794/79. In this endoscope, an air feed passage and a water feed passage are formed internally, and an air/water feed selector valve mechanism is provided so that the air or water feeding operation may be selected by switching an air/water selector valve. Also, an operating valve mechanism is used to feed compressed air into the water feed passage, thereby removing water from the water feed passage. In the endoscope of this construction, however, both the air/water feed selector valve mechanism and the operating valve mechanism require a manual valve switching operation by an operator. Thus, the operation is complicated and troublesome, and it is hard to judge whether the valves are in a water feeding state or whether they are in a draining state. Such a situation could easily lead to incorrect operation and would be hazardous.